The present invention relates to a disk drive where control of read-ahead is implemented for parallel execution of realtime processing and non-realtime processing so that realtime processing performance is raised while data transfer speed is raised for non-realtime processing.
For realtime processing such as AV data processing, disk drives must accurately follow the prescribed temporal rules to execute data transfers. Thus, in order to secure realtime performance, it is being considered to introduce in the ATA/ATAPI-7 (under standardization according to the ANSI rules) a command set which allows stream-specific or command-specific time limits to be set for AV data processing. In addition, read-ahead is carried out in disk drives by using free periods (mainly rotational latency periods) between commands executed in order to raise the speed of data transfer to the hosts. A control method for such read-ahead is described in Patent Document 1 (Japanese Patent Laid-open No. 6-95810).